JPH08194133A - Optical connector and its production - Google Patents

Abstract

PURPOSE: To provide an optical connector with which the shapes of positioning pins after mounting of optical fiber are settable with high accuracy and a process for producing this connector. CONSTITUTION: This optical connector is formed to fix the optical fibers into optical fiber mounting holes 18 by the adhesives injected from an adhesive injection hole 19 into a ferrule 13 formed with the positioning pin holes 17 to be fitted with the positioning pins, the optical fiber mounting holes 18 to be mounted with the optical fibers and the adhesive injection hole 19 communicating with these optical fiber mounting holes 18. The positioning pin holes 17 before injection of the adhesive into the adhesive injection hole 19 are so formed as to be curved to project in the middle to about 2 to 5μm on the adhesive injection hole 19 side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical connector for connecting a pair of optical fibers to each other and a manufacturing method thereof.

[0002]

2. Description of the Related Art FC type connectors for single-core wires and S
A C-type connector or an MF-type connector mainly for multi-core wires is an optical connector for connecting a pair of optical fibers or a group of optical fibers to each other.
This is well known in Japanese Laid-Open Patent Publication No. 606, JP-A-4-347806, etc., and these all have a structure in which housings are connected to each other via an adapter on the assumption that they are frequently attached and detached.

As shown in FIG. 3 showing the appearance of such a conventional optical connector, optical cables 11a and 11b are respectively provided.
The ferrules 13 of the optical connectors 12a, 12b to which the tip ends of are fixed are connected with their joint end faces 14 abutted to each other via a clip (not shown).
A pair of positioning pins 16 having a diameter of, for example, about 0.7 mm and processed with high precision are slidably fitted to the joining end surface 14 of each ferrule 13 facing the end surface of the optical fiber 15 in the optical cables 11a and 11b. Positioning pin holes 17 are formed. By tightly fitting the positioning pins 16 into the positioning pin holes 17, the distal end faces of the optical fibers 15 facing the joint end faces 14 of the ferrules 13 of the pair of optical connectors 12a and 12b are aligned in a straight line. It is supposed to do.

The ferrules 13 of the optical connectors 12a and 12b as described above are usually manufactured by molding a resin, and the central longitudinal section along the longitudinal direction of FIG. 4 showing the appearance of the ferrule 13 immediately after molding is shown. As shown in FIG. 5 showing the surface structure and FIG. 6 showing the longitudinal sectional structure along the positioning pin hole 17, the ferrule 13 immediately after this molding is formed.
Includes a pair of positioning pin holes 17 into which the positioning pins 16 are respectively fitted, and one or a plurality (four in the illustrated example) of optical fiber mounting holes 18 through which the optical fibers 15 are inserted.
Adhesive injection hole 1 communicating with these optical fiber mounting holes 18
9 and the positioning pin hole 17 and the optical fiber mounting hole 18 correspond to the contour shape of the ferrule 13, and the positioning pin hole 17 and the optical fiber mounting hole are formed in a cavity formed in a molding die (not shown). After arranging the molding pins (not shown) for forming 18 in the respective positioning states, a molding resin such as a thermosetting epoxy resin containing about 8% of silica powder as a filler is injected into this cavity, and after curing, these are molded. By pulling out the molding pin, the ferrule 13 with the highly accurate positioning pin hole 17 and the optical fiber mounting hole 18 formed therein can be removed from the molding die. Then, the tip ends of the optical cables 11a and 11b are inserted into the ferrule 13, the optical fiber 15 in the optical cables 11a and 11b is passed through the optical fiber mounting hole 18, and then the thermosetting adhesive is injected from the adhesive injection hole 19. Is injected to integrate the optical fiber 15 and the ferrule 13.

Reference numeral 20 in the drawing denotes each optical fiber 1 so as to form a straight line with respect to the optical fiber mounting hole 18.
5 are V-groove-shaped optical fiber guiding portions which are parallel to each other for positioning the optical fibers 5.

[0006]

When the optical fibers 15 are respectively connected to the ferrules 13 of the optical connectors 12a and 12b shown in FIG. 3, since the thermosetting adhesive is used as described above, this As shown in FIG. 7, the ferrule 13 is deformed such as warped due to the volume contraction accompanying the curing of the adhesive, and the positioning pin hole 17 is also curved accordingly. The warp of this ferrule 13 is
This occurs around the adhesive injection hole 19 of the ferrule into which the adhesive is injected, and its deformation amount is determined according to the curing shrinkage amount of the adhesive and the rigidity of the ferrule 13.

When the axis line of the positioning pin hole 17 into which the positioning pin 16 is inserted is curved due to the warp of the ferrule 13, the light beams held by the pair of optical connectors 12a and 12b connected to each other through the positioning pin 16 are respectively held. The connection end faces of the fibers 15 do not face each other, leading to an increase in connection loss. Also, the optical connectors 12a, 12b
The local wear of the positioning pin hole 17 progresses due to the repeated attachment / detachment operation of the positioning pin 16 and the positioning pin hole 1.
As a result, the rattling of the optical fiber 15 gradually increases and the positioning accuracy of the pair of optical connectors 12a and 12b decreases, resulting in an increase in the connection loss of the optical fiber 15.

When the adhesive injection hole 19 is set small, the ferrule 13 of the optical connectors 12a and 12b is used.
Since the amount of adhesive injected inside can be reduced,
Although the amount of deformation of the positioning pin hole 17 can be suppressed, the adhesive injection work is hindered, and therefore the reduction of the adhesive injection hole 19 cannot be adopted as a practical problem. Further, the optical fiber mounting hole 18 has a depth of only about 2 mm from the joining end surface 14 of the ferrule 13 having a total length of about 8 mm, and is apart from the adhesive injection hole 19, so that the influence of the warp of the ferrule 13 is exerted. I rarely get it.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical connector manufacturing method capable of setting the shape of a positioning pin hole after mounting an optical fiber with high accuracy.

[0010]

According to a first aspect of the present invention, a positioning pin hole into which a positioning pin is fitted, an optical fiber mounting hole into which an optical fiber is mounted, and a communication hole to the optical fiber mounting hole. An optical connector in which an optical fiber is fixed to the optical fiber mounting hole by an adhesive injected from the adhesive injection hole with respect to a ferrule in which an adhesive injection hole is formed. The optical connector is characterized in that the positioning pin hole before the adhesive is injected into is curved so as to be convex inward toward the adhesive injection hole side.

Here, the center of the central portion along the longitudinal direction of the positioning pin hole is 2 with respect to the axis passing through the center of both ends of the positioning pin hole before the adhesive is injected into the adhesive injection hole. It is preferable that the deviation is ˜5 μm.

A second aspect of the present invention is a positioning pin hole into which a positioning pin is fitted, an optical fiber mounting hole in which an optical fiber is mounted, and an adhesive injection hole communicating with the optical fiber mounting hole. In a method for manufacturing an optical connector, wherein an optical fiber is fixed to the optical fiber mounting hole with an adhesive injected from the adhesive injection hole with respect to the ferrule in which is formed, In the method of manufacturing an optical connector, the positioning pin hole is formed in consideration of the deformation of the ferrule due to the curing of the adhesive so that the positioning pin hole has a linear shape.

Here, a resin molding process of the ferrule is performed in a state where the molding pin for molding the positioning pin hole is bent, and the molding pin is removed after the resin is hardened, so that a desired positioning pin hole is formed. Can be formed into a ferrule.

[0014]

[Function] When the optical fiber is fixed to the ferrule by injecting the adhesive from the adhesive injection hole, volume contraction occurs as the adhesive hardens, so the ferrule is centered on the adhesive injection hole side It has a tendency to warp in a concave shape.

Therefore, the positioning pin hole formed in advance on the ferrule is formed into a convex shape toward the adhesive injection hole side, and is along the longitudinal direction of the positioning pin hole with respect to the axis passing through the center of the opening at both ends of the positioning pin hole. The center of the center is 2
By bending the ferrule so that it is displaced by -5 μm, the axis of the ferrule becomes a straight line when warped.

Such a ferrule is obtained by molding a resin in a state where a molding pin for molding a positioning pin hole is bent, and removing the molding pin after curing the resin.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical connector and a method of manufacturing the same according to the present invention will be described in detail with reference to FIGS.

First, the optical connector 1 produced by the conventional method
2a and 12b, an epoxy thermosetting resin is used as an adhesive for connecting the ferrule 13 and the optical fiber 15 as shown in FIG.
The optical fiber 15 is fixed to the ferrule 13 by injecting from 9 and the positioning pin hole 1 due to the curing shrinkage of the adhesive at this time
The deformation amount of 7 was measured. As a result, the positioning pin hole 17
The center of the positioning pin hole 17 in the central portion along the longitudinal direction of the ferrule 17 is displaced by about 3 μm from the axis connecting the opening centers of both ends of the positioning pin hole 17
It was found that was deformed into a concave shape on the adhesive injection hole 19 side (see FIG. 7).

Therefore, as shown in FIG. 1, the ferrule 1 is attached to the axis connecting the centers of both ends of the positioning pin hole 17.
The center of the central portion of the positioning pin hole 17 along the longitudinal direction of 3 is preliminarily shifted in the opposite direction by about 3 μm, and the ferrule 13 having the positioning pin hole 17 which is convex toward the adhesive injection hole 19 side is prepared. Use the adhesive from this ferrule 1
The ferrule 13 is injected through the adhesive injection hole 19
After fixing an optical fiber (not shown), the deformation state of the positioning pin hole 17 was measured, and as a result, it was confirmed that the positioning pin hole 17 had a substantially straight line shape as shown in FIG.

Here, as a method of manufacturing the ferrule 13 having the positioning pin hole 17 which is convex inward on the side of the adhesive injection hole 19 as shown in FIG. 1, the ferrule 13 is manufactured by resin molding. Positioning pin to be positioned in the cavity of the molding die Hole The molding pin for molding is bent in advance to a predetermined curvature, or a predetermined bending moment is applied, and this molding is performed after the resin is cured in the cavity. A method of removing the pin can be adopted.

The bending amount of the positioning pin hole 17 is 2
If it is less than μm, the effect on the connection loss is negligible, and if it is more than 5 μm, it is necessary to use an adhesive with a large amount of curing shrinkage, so that the effect of the presence of the adhesive injection hole 19 is large. However, it becomes difficult to control the deformation with high accuracy.

The degree to which the positioning pin hole 17 deforms together with the ferrule 13 due to the volume contraction accompanying the curing of the adhesive changes depending on the components of the adhesive and so on. It is necessary to adjust the bending degree of the positioning pin hole 17 in advance. Further, even when the same adhesive is used, it is desirable to always keep the curing conditions of the adhesive constant because the warping conditions of the ferrule 13 and the positioning pin hole 17 change depending on the curing conditions.

[0023]

According to the optical connector and the method of manufacturing the same of the present invention, the positioning pin hole is formed in consideration of the deformation of the ferrule due to the curing of the adhesive so that the positioning pin hole after the curing of the adhesive has a linear shape. Since it is molded, the axis line of the positioning pin hole formed in the ferrule after fixing the optical fiber becomes a straight line, and the positioning pin can be smoothly fitted into the positioning pin hole The pin can be held perpendicular to the connection end face of the optical connector.

As a result, when the optical connector is coupled through the two positioning pins, the increase of the connection loss can be suppressed to the minimum and the optical fiber can be stably connected. Further, even when the optical connector is attached / detached, local abrasion of the positioning pin hole can be prevented in advance, and fluctuations in connection loss due to attachment / detachment of the optical connector can be suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view taken along a positioning pin hole showing an embodiment of a ferrule of an optical connector according to the present invention.

FIG. 2 is a cross-sectional view of a state in which the ferrule shown in FIG. 1 and an optical fiber are joined together.

FIG. 3 is a perspective view showing an appearance of an optical connector which is a subject of the present invention.

FIG. 4 is an enlarged perspective view of a ferrule portion of the optical connector shown in FIG.

5 is a central longitudinal sectional view of the ferrule shown in FIG.

6 is a vertical sectional view taken along a positioning pin hole of the ferrule shown in FIG.

FIG. 7 is a sectional view showing a state in which a conventional ferrule and an optical fiber are joined together.

[Explanation of symbols]

 11a, 11b Optical cable 12a, 12b Optical connector 13 Ferrule 14 Joining end face 15 Optical fiber 16 Positioning pin 17 Positioning pin hole 18 Optical fiber mounting hole 19 Adhesive injection hole 20 Optical fiber guide part

Claims (4)

[Claims] 1. A ferrule having a positioning pin hole into which a positioning pin is fitted, an optical fiber mounting hole into which an optical fiber is mounted, and an adhesive injection hole communicating with the optical fiber mounting hole, An optical connector configured to fix an optical fiber to the optical fiber mounting hole by an adhesive injected from the adhesive injection hole, wherein the positioning pin hole before the adhesive is injected into the adhesive injection hole is An optical connector, which is curved so as to be convex toward the adhesive injection hole side. 2. The center of the central portion along the longitudinal direction of the positioning pin hole is 2 to the axis passing through the center of both ends of the positioning pin hole before the adhesive is injected into the adhesive injection hole. The optical connector according to claim 1, wherein the optical connector is offset by 5 μm. 3. A ferrule having a positioning pin hole into which a positioning pin is fitted, an optical fiber mounting hole into which an optical fiber is mounted, and an adhesive injection hole communicating with the optical fiber mounting hole, In a method of manufacturing an optical connector in which an optical fiber is fixed to the optical fiber mounting hole by an adhesive injected from the adhesive injection hole, the positioning pin hole after the adhesive is hardened has a linear shape. In the method for manufacturing an optical connector, the positioning pin hole is formed in consideration of deformation of the ferrule due to hardening of the adhesive. 4. The molding pin for molding the positioning pin hole is subjected to resin molding of the ferrule in a bent state, and the molding pin is removed after the resin is cured. 3. The method for manufacturing the optical connector described in 3.